Poorly healing skin wounds, such as burns, diabetic ulcers, and pressure ulcers, are a significant worldwide health concern. During wound repair, changes in extracellular matrix (ECM) control healing processes including re-epithelialization. In intact skin, the epidermis is separated from the underlying dermis by the basement membrane (BM). Upon injury and breaching of the BM, keratinocytes at the wound edge de- differentiate and gain a fibroblast-like (or migratory) phenotype to close the wound. Earlier studies demonstrated that collagenase-1 (MMP1) is required for the ability of human keratinocytes to move over the viable dermal ECM and indicated that ligation of the 1221 integrin with dermal ECM signals to induce expression of MMP1 in keratinocytes at sites of injury. However, the signaling events and pathways that control MMP1 expression in keratinocytes have not been determined. The objectives of this proposal are to study the signaling and epigenetic mechanisms controlling expression of MMP1 and keratinocyte migration during wound healing. Specifically, we hypothesize that the Rho GTPase pathway and DNA methylation are critical control points regulating MMP1 and hence, epidermal re-epithelialization. Furthermore, we also hypothesize that the re-differentiation of wound keratinocytes at the completion of repair, which involved the turn off of MMP1, among changes in many other genes, is controlled by specific cell-matrix interactions. This idea will be addressed by assessment of global gene expression, and advanced bioinformatic tools will be used to predict key regulatory proteins, whose function in ECM-dependent keratinocyte differentiation will be validated by experimentation. In accordance with the mission of NIAMS to improve health outcomes for patients with skin diseases, this fellowship proposal will examine the cell signaling regulation at wound injuries and may identify changes in wound healing that result in chronic wound or malignancy. PUBLIC HEALTH RELEVANCE: The studies in this proposal will attempt to define the signaling mechanisms regulating wound repair. Understanding the basic signaling molecules and events benefit the field when translation into therapeutic use against diseases such as chronic wounds is needed.